Impaired cerebral autoregulation in patients with moyamoya disease and moyamoya syndrome: A prospective cross-sectional study.

Moyamoya disease and syndrome (MMDS) are rare cerebrovascular etiologies defined by stenosis of the distal intracranial internal carotid artery and proximal branches, with secondary development of small-vessel collaterals. Current techniques to characterize MMDS severity generally provide measurements in resting conditions (degree of stenosis, vessel collateralization, and regional oxygen delivery). In addition, some measurements of cerebral perfusion are performed with induced hypercapnia or acetazolamide to assess chemoreactivity. Despite the battery of exams, current techniques do not provide information about cerebral autoregulation. This study aimed to investigate dysfunction of cerebral autoregulation among patients with MMDS. Metrics of cerebral autoregulation were determined by transfer function analysis (TFA) of Middle Cerebral Artery velocities obtained with transcranial doppler ultrasound. Fourteen adult patients with MMDS and fifteen healthy, age- and sex-matched controls were included. Metrics of TFA (gain, phase, and coherence) were obtained within three frequency ranges (very low frequency (0.02-0.07 Hz), low frequency (0.07-0.2 Hz), and high frequency (0.2-0.5 Hz), in alignment with recommendations from the International Cerebral Autoregulation Research Network. Compared to the control group, the MMDS group had a significantly lower, very low frequency phase (P = 0.005), low frequency phase (P < 0.001), and high frequency phase (P = 0.010). In addition, the MMDS group had a significantly lower, low frequency coherence (P = 0.033). Regression analyses demonstrated a significant association between Suzuki grade and low frequency gain (m=-0.283, R2=0.089, P = 0.045) and high frequency gain (m=-0.338, R2=0.115, P = 0.026). Among patients with MMDS, there was a significant association between breath-hold index and low frequency phase (m=11.78, R2=0.171, P = 0.045), low frequency coherence (m=0.08, R2=0.242, P = 0.015), and high frequency coherence (m=0.06, R2=0.380, P = 0.001). Overall, these findings highlight a notable impairment in cerebral autoregulation in MMDS that appears to be associated with disease severity. Further studies are needed to assess whether cerebral autoregulation predicts disease progression and outcomes after surgical revascularization in MMDS patients.